HACKENSACK -- The feud between Alex Rodriguez and the Yankees has escalated into an all-out civil war.

And it was waged publicly Wednesday over the embattled star’s strained left quadriceps — and the quasi-second opinion of a Hackensack University Medical Center doctor who disputed the team’s diagnosis.

The drama and intrigue surrounded not just the Yankees’ $275 million player, but Dr. Michael L. Gross — the hospital’s chief of sports medicine — who reviewed an MRI of Rodriguez’s quad at his request and found no evidence of injury, he told The Record and other media outlets.

But the orthopedic surgeon admitted he did not examine Rodriguez in person and only spoke to him over the phone.

“I looked at his MRI and I didn’t see anything significant,” said Gross, sitting in his Hackensack office. “[That] doesn’t mean there’s not an injury there.”

Rodriguez’s camp reportedly hoped Gross’ opinion would serve as evidence that he is fit to play, contradicting the Yankees. The team doctor diagnosed a Grade 1 strain Sunday and shut him down, one day before Rodriguez — reportedly facing a lengthy suspension for alleged performance-enhancing drug use — was scheduled to rejoin the team for the first time since off-season hip surgery.

The Yankees fired back Wednesday evening.

General manager Brian Cashman said in a statement that “Contrary to the Basic Agreement, Mr. Rodriguez did not notify us at any time that he was seeking a second opinion from any doctor with regard to his quad strain.”

Cashman added that Rodriguez first complained of quad “tightness” July 12 and refused to move from Class A Tampa to Class AAA Scranton/Wilkes-Barre because of it.

“As you know, it is the Yankees’ desire to have Alex return to the lineup as soon as possible,” Cashman said.

“And we have done everything to try and accomplish this.”

A team spokesman told reporters that the Yankees did not release a copy of the MRI to Gross. They will re-evaluate Rodriguez today.Gross also found himself scrutinized — and with a recent past that includes steroids.

He was approached by a mutual friend of Rodriguez’s and had “never met A-Rod before today,” he said Wednesday.

Despite the firestorm, the doctor said he had no regrets.

“Nobody paid me. I just did it as a favor,” said Gross, who has practiced in Bergen County since 1989. “... I thought it would be fun. It’s my five minutes of fame.”

Gross admitted he could not clear Rodriguez without examining him in person. But he said a lack of pain led him to conclude that the third baseman isn’t injured — or has healed.

“I asked, ‘Does it hurt?’ He said no,” Gross said. “I said, ‘Well then that conversation should end here.’”

Gross added he “maybe” saw “some abnormalities” on the MRI, but nothing near a marker on the scan showing where the injury was, he said.

He called Yankee team doctor Dr. Christopher Ahmad — who made the diagnosis — but had not heard back as of Wednesday afternoon.

Despite his lofty position at a respected hospital, Gross was reprimanded in February by the New Jersey State Board of Medical Examiners for issues involving a wellness clinic he runs, Active Health and Wellness Center.

He was found to have hired someone who did not have a license to practice medicine and for not properly ensuring patient treatment “involving the prescribing of hormones including steroids,” according to documents.

Gross was fined $40,000 and ordered to attend an ethics course.

He became ensnared in just the latest squabble between Rodriguez and the team over his rehab. But the real battle concerns not the star’s quad, but the possible lifetime ban for his possible involvement in the Biogenesis scandal.

And it concerns the four years and $86 million remaining on his contract.

The Rodriguez-Yankees feud went nuclear Wednesday when Gross appeared on WFAN radio, saying he found no evidence of an injury.